383 Engine Build - Three Eighty Three: Some Machining Required

Quarter Mile Performance Machines & Preps Our Bare Block

We've run everything from complete crate engines to short-block builds on the dyno; most of which have seen success. Ground up engine builds still garner most of the attention though. There's just something about doing things yourself. It's the mindful approach that allows the builder to maintain an overall sense of control and allows them to pay careful attention to details. Obviously, there are plenty of preassembled stroker short-blocks available, but this time around we're going back to our roots and starting from ground zero.

It all starts with a bare block, and to handle ours we headed to Quarter Mile Performance (QMP) in Chatsworth, California, for a more hands on approach for our machine work. There, we completely prepped our bare four-bolt main 350 small-block from Engine Quest for its new life as a 383ci street brawler.

With our core in hand, we sent it through the ringer and gave it an align-hone, bore, deck, and hone; we even did a bit of clearancing for the longer rods on the CNC mill. This is something you're going to have to source out, so follow along as we detail our block's journey from bland to bold. The next time you see our block, we'll be installing a complete stroker rotating assembly from Eagle Specialty Products and topping it off with Edelbrock heads and manifold.

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383 Engine Build - Three Eighty Three: Some Machining Required

Engine cores are becoming more difficult to find. The good news is, Engine Quest can fill your order and have it shipped to any destination. Priced at $300 (CH350BB), Engine Quest located a solid four-bolt main core that was even magnaflux and bake-blasted prior to shipping.

Our bare block came complete with a full set of main caps and bolts with a two-piece rear main seal. All '55-85 small-block Chevys were built with the two-piece rear main seal design. Any '86-and-newer block will come with a one-piece rear main seal. Take this into consideration when ordering or sourcing a crank.

Super-Torque
Proper tools and supplies for a job of this magnitude are a must. We picked up a bottle of ARP Ultra-Torque (PN ARP-100-9910) fastener assembly lubricant. Typically, when a fastener is first tightened, friction is at its greatest amount and the preload value, or stretch, is at its lowest. For example, with head bolts this can cause bore distortion, hamper piston ring seal, and lead to poor head gasket sealing. When the fastener is cycled over and over, friction decreases and preload increases. The Ultra-Torque assembly lubricant allows the fastener to be torqued once to become within 5 percent of its ideal preload. Plus, that load remains consistent from race-prep machining to final assembly.

Right out of the crate, we loaded our bare block into the align-hone machine at QMP. We numbered and removed all the main caps. Using a machining stone and some wet/dry sandpaper on the bottom side of where the caps install will smooth out any high spots. It also gives the newly cut caps a smooth surface to bolt to.

We set aside the factory main bolts and upgraded to a much stronger set of 12-point main bolts from ARP (PN 234-5201). Priced very reasonably at just $79, they offer peace of mind for any performance build. We applied a liberal amount of Ultra-Torque lube to the threads and shoulder of each bolt.

Michael Consolo cut each cap, removing 0.010-inch of material right off the bat. This gave each cap a flat surface and a nice starting point once the caps were bolted back on for honing.

Paying close attention to detail, Consolo used a hand file to chamfer the edge of each cap. Removing any sharp edges at this point prevents the stone from getting snagged on the cap during the honing process. From there, each cap was washed in solvent to remove any excess material or debris.

The main caps now had a perfectly flat surface. Following our numbered caps, we installed each cap (tang to tang), threaded in our fasteners, and torqued each one down to 65 ft-lb, beginning from the center cap (No. 3) and moving outward.

The honing process took just over 30 minutes. Preventing the mains from overheating and expanding is critical during the course of honing. Consolo checked with dial calipers to reveal two things: Our center cap looked good, but the rear cap was still too large. The cap was then removed, cut, and reinstalled. Additional passes of the hone revealed 2.6410 inches from the dial indicator. Some hones have a tendency to taper the mains, so flipping the block around eliminates the inconsistency in the machining process and will help keep things in line.

Removing the factory head dowels will help expedite the machining process. Our particular block needed to be decked to create a new surface. Using a special puller, we removed each dowel with care.

Taking full advantage of QMP's facilities, we opted to deck, bore, clearance, and chamfer our block in the fully automated CNC mill. We've learned that a limited number of machine shops have access to one. Automation's an added bonus as it eliminates any measuring errors that may occur with a manual decking, boring, or resurfacing machine. Another advantage is how quickly blocks can be machined and handed back to you for final assembly, which can be crucial for many builders.

Bore Sizes
Our factory bore sizes were less than ideal. Here, on the CNC's screen we could clearly see each cylinder's bore size. The largest bore before cutting was 4.0073 inches and our smallest came in at 4.0023 inches.

Taking over the reins on the CNC mill, Brad Lagman began to map out our assault on the block. After setting the cutting tool and with the touch of a button, Lagman ordered an immediate 0.030-inch be removed from each cylinder to a depth of 5.900 inches. Not only did the CNC bore each cylinder to precise specs, it also bored deep enough to clearance for the honing process. After boring, the CNC head moved over 0.0010-inch and dropped to a depth of 6.200 inches. From there, a step-notch is created in the bottom of each cylinder, allowing the bore-honing stones ample room to spin, once again eliminating bore taper and broken stones.

Decking the surface of the block was next. Visibly, a thick layer of rust had accumulated on the surface and had to be removed. During the automated probing of the surfaces, our lowest deck height came in at 9.0084 inches. Each pass on the CNC removed about 0.004 inch of material, until the surface was as smooth as glass. All in all, our factory block was milled to 9.007 inches.

A cutter was used to remove the top edge of its cylinder wall material. Separating QMP's technical level of machining from others, the company designed a chamfering program for the tops of each cylinder. Galling the piston skirts or snapping rings is no longer an issue.

Fruits Of The Labor
Our block was close to complete when it came out of the CNC machine. (A) Here, the clearancing of the bottom of each cylinder is evident. While this could take a full day of grinding, QMP's programming performed the same job in 4 minutes, 9 seconds. (B) Our cylinder walls were completely bored and perfect. (C) Note the bottom clearancing of the block to allow a full sweep of the bore honing stones.

Spending extra time to chase the head bolt threads is always a good idea. Here, we used a 7/16-inch thread tap to clean and debur the factory head boltholes, which ensures proper loading of the bolts.

QMP ditched the traditional style hone-torque plate for their custom designed torque plate, which mimics a small-block aluminum cylinder head, allowing them to emulate the load when honing the cylinder walls.

For the final step, QMP usually implements a four-step honing process that utilizes four different stones to achieve a smooth surface. The final step of honing uses a Delron shoe and micro brush to create a super-slick cylinder wall surface. From here, we'll give the block a well deserved wash and a fresh coat of paint.

Check out Vette's progress on this high-performance 418ci stroker engine! At its core is an LS3 block, ported PRC L92/LS3 heads, a Comp hydraulic roller cam, and much more. At baseline testing, this motor stood at 608 hp at 6,300 rpm and 561 lb-ft of torque! Check out further details and pictures at Vette Magazine. » Read More